Though you should maintain a healthy diet throughout your pregnancy, nutrition is especially important during the third trimester.

By Susan Dahlheimer, PhD, RD, FADA, and Diane Wagoner, MS, RD, LDN

In your last months of pregnancy, nutrition should be a consideration at every meal. Right now, as your baby is preparing to live outside of your body, she’s developing at a rapid pace: Her lungs and kidneys are growing stronger so that they can take over the functions that yours are now performing, and her brain is quickly maturing. At the same time, your body is preparing to produce milk, so you can continue to nurture your baby when breastfeeding in the coming months. The food choices you make now will help ensure a healthy start for your baby and positive eating habits for your growing family.

In 2010, USDA Center for Nutrition Policy and Promotion released new dietary guidelines. Called MyPlate, the new design emphasizes healthy food choices (such as switching to skim or 1% milk and filling your plate at least halfway with fruits and vegetables); cutting back on foods high in solid fats (such as butter and vegetable shortening), added sugars, and salt; and eating the right amount of calories for you. Guidelines for pregnancy and breastfeeding are also included.

Start with Energy

In the last trimester, babies typically gain about a quarter to a half-pound each week. To ensure this steady growth pattern, you must eat enough to gain about a pound per week, which will require about 300 extra calories a day. Your extra energy consumption also helps your blood volume increase, so it can supply enough nutrients to the baby, prepare your breasts for milk production and build strong muscles to support labor. Never try to lose weight or restrict your calories during pregnancy. If you do, you are likely to feel depressed, anxious and stressed, and your baby is more likely to be born early, small and less prepared for life outside the womb.

Build a Base with Protein

Protein’s importance in your diet is second only to caloric intake. During pregnancy, you need about 20 percent more protein than normal for increased fetal growth, uterus and breast development, and preparation for breastfeeding. If your diet meets the pyramid’s recommendations of five to seven ounces of protein foods and three cups of milk a day, you probably are already consuming enough protein to meet your needs and those of your growing baby.

Focus now on your source of protein: Fish, meat, poultry, eggs and dairy should be a big part of your diet. Because dangerous mercury levels in some fish can impair a baby’s brain development, the FDA recommends that you avoid eating large predator fish such as swordfish and king mackerel. However, it is safe to eat up to 12 ounces a week of more commonly consumed fish such as cod, salmon and canned light tuna. If your fish comes from a local water source, do a check to make sure it is free of pollutants and safe to eat.

Lacto-ovo vegetarians - those who eat dairy and eggs but not meat - should increase their consumption of dairy products and supplement their diet with protein from beans, seeds and nuts. Vegans - those who eliminate all animal products, including dairy, fish and eggs - should be sure to get enough enriched soy milk, tofu, cooked beans, nuts and nut butters. A vegan diet lacks the vitamin B12 from meat and dairy foods that is vital for red blood cell production, brain development and metabolism, so vegans will need to compensate with fortified soy products or supplements.

Vary Your Diet

During pregnancy, nutrition requirements increase across the board: Your need for folic acid, iron and vitamin B6 rises by about 50 percent because these nutrients promote the formation of healthy red blood cells and reduce your risk of developing anemia during pregnancy and birth. In addition to helping supply oxygen to all tissues, these nutrients participate in cell division and protein synthesis, making them especially important during this time of rapid fetal growth.

Folacin, or folic acid, is contained in leafy dark green vegetables (such as spinach and romaine lettuce), legumes and citrus fruit. However, because most people consume relatively low amounts of folacin, it is also added to many grain products that are designated “fortified,” such as cereal, bread, pasta and flour. To get enough iron, choose fortified cereals that supply 100 percent of the FDA’s recommended daily value of 27 milligrams per day for pregnant woman. Eat foods rich in vitamin C (citrus fruits, tomatoes and green peppers) with iron-rich ones (fortified grain products) to enhance your ability to absorb iron. Lean meats also provide an excellent source of iron that is easily absorbed without the addition of vitamin C. Vitamin B6 is found in whole grains and fortified cereals, meat, poultry, fish and beans.

Drink Enough Fluids

During the last trimester, several changes in your body increase your need for fluids. By this time, your blood volume has risen by about 50 percent so that nutrients can easily be transported to the placenta. Also, food is now passing more slowly through your intestines, increasing the chance of constipation. So keep the fluids coming: You’ll need them to maintain the extra blood supply, and adequate fluids combined with dietary fiber can help prevent constipation.

You may also notice that you get more tired if you are dehydrated - and you need all the energy you can muster these days. Drink at least eight to 10 cups of water or milk daily. You may also substitute some of your fruit and vegetable servings with juice, although it lacks the fiber found in whole fruits and vegetables. Try to get an extra serving of milk each day to help your baby grow strong bones and reduce your risk of osteoporosis later in life.

Relieve Heartburn

Heartburn is a common pregnancy complaint. It occurs because the growing baby puts increased pressure on your stomach, while hormones relax the muscles that close the esophagus, allowing stomach acid to rise. To prevent or reduce heartburn, try to relax and eat slowly. Eat small meals when you’re hungry, even if that is six or more times a day. Gravity can help keep the acids settled in your stomach, so sit up while you eat, and avoid lying down for at least an hour after a meal or snack. You may find that very spicy or greasy foods increase heartburn, so try to avoid them late in the day.

Listen to Your Body

To gauge your caloric needs, pay attention to your hunger cues: That way you’ll follow a naturally healthy weight-gain pattern. Don’t wait until you’re ravenous. If you do, you’re more likely to eat large amounts of unhealthy foods.

Maintaining a nutritious diet during these last important months before birth will impact your health and that of your baby. For most women, food tastes better than ever at this time in pregnancy. That’s why it’s an ideal time to enjoy eating as you anticipate your new arrival.

Petra Colindres, Family Dietitian, Lactation Consultant and owner of Nutrition by Petra in Oklahoma City. Petra hones in on the most important nutrients needed by trimester. Take a look and consider r...

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